This page focuses on the variety of old telephone numbers that begin with two and three letter prefixes. In theory, there are smaller four and five digit telephone numbers that would have been used prior to 1892. I highly doubt any of those will be floating around.

From 1892 to 1921, one would have placed a call by telling the operator the name of the exchange, followed by the callee’s specific number. For example, present day (773) 525-0421 would have been Lake View 421. Apologies to whomever currently has that number. In 1921, this was changed to a 3 letter – 4 digit system. Our example number becomes LAK-0421. This was cut back to 2 letter -5 digit (2L-5D) in 1948, lasting officially until 1977. Area codes were introduced in 1947, however, the issue does not become confusing in Chicago until 1996. Our number in 1948 became (312) LA5-0421. 2L-5D is the variety that remains…if you look hard enough.

Exchange prefixes were not necessarily based on a logical location. There were some common ones recycled from city to city. However, some do refer to local landmarks.

Left: Before we were armed with a list of the two letter codes, telling us what they meant, we were left to make a guess based on the location. This was also before we knew that the format was changed from 3L-4D to 2L-5D in 1948. The first number in the five number version, taking the five in “CA 5-6969″ for example, refers to the third letter in the word (Calumet), in this case ‘L’. As stated earlier, these are not always based on proximity to what the name refers. We thought “AV 3″ meant Avondale, considering the sign is in Portage Park. It actually means Avenue, which makes little geographic sense, not considering the fact that “o” in Avondale would not have been a three.

Right: Sometimes they do make sense. LaSalle Flower Shop is on LaSalle and Huron, not far from SUperior Street.

Left: The “SH 3″ designation annoys the crap out of me. This one is on the rear of a building on Broadway just south of Granville. Not too far from Sheridan Road, and it would fit, alphanumerically. On our list however, SH 3 means Sheldrake! What the hell is Sheldrake? Maybe the list is wrong.

Right: At right, we have the Philadelphia Wire Frame Company, with the ubiquitous CA 5 prefix. CA 5 stands for Calumet, which makes this sign an amusing mix of misnomers. This company is not located in Philadelphia, nor is their telephone exchange near the Calumet region – since demolished, it was located at 1824 S. Wabash.

Left:The CA 5 prefix applied to the Near South Side – Motor Row area, which is where this well kept sign is – 18th and State. It is the only old exchange number we’ve seen that has obviously been painted recently. This sort of thing happens with some frequency in New York, but has all but been abandoned here.

Right: The “VI 6″ sign was spotted in Gresham, not terribly far from VIncennes Avenue. This picture shows two different ways to look at the same telephone number. Remember, 773 didn’t exist until 1996.

Left:The sign at left is difficult to read, but has not just two numbers, but two prefixes in one! They are “CE 6″ and “DE 7″, which mean Central and Delaware respectively.

Right: Another difficult one to read, the number at right says “MO 4″ something. Note the address on the ad is 319 W. Ontario, the building on which the ad is painted.

Left:“MO 4″ means Mohawk, which we never would have guessed. Our first thought was Missouri, which shows that our first thought usually needs heavy editing. Because the sign is missing its first letter, we will pretend it says “Bartman’s.” Or “Cartman’s”…you get the idea. Merchandise Mart towers in the background of this image.

Right: Concluding our first set of these numbers is a well faded ad for a printing supply company. Can you guess where this is based on the clues in the ad? Why, Union Row of course! “TA 9″ means Taylor, which this ad, at Adams and Ashland, is a mere mile (or so) from.